Implementation of rev(1B) (#52)

* feat: Initial implementation of rev(1).

* chore: No need to use printf() if we could just puts().

* chore: Close string correctly.

* chore: Mention new rev(1B) implementation at CHANGES.

* chore: rev refactor.

* feat: Added (rudimentary) multibyte support for rev.c.

* feat: Full support for UTF-8 multibyte at rev(1).

Borrowed from suckless sbase implementation, as mentioned on the header.

* chore: Update CHANGES

* docs: Added manual page for rev(1).

* chore: Added rev/ to the build list at the top 'makefile'.

* chore: Mention where UTF-8 support at rev(1) comes from in CHANGES

CHANGES

@@ -1,9 +1,11 @@
 Release ...
+* rev: UTF-8 support, borrowed from suckless sbase. In varietate concordia.
 * [NEW] apply, pick: Complete implementation for both apply and pick, from
   Research UNIX 8th and 10th respectively; extended payloads for pick in
   comparison with the original implementation.
 * seq: Support for counting from negative numbers to positive or making a
   negative sequence.
+* rev: Full refactor (made by Samuel Brederodes).
 * Fixes for building dynamically on Arch Linux and other GNU C
   Library-based Linux systems which ships exclusively dynamic versions
   of its libraries, also remove `readlink_ucb' object file at `readlink/'
@@ -13,6 +15,7 @@ Release ...
   is not used as much on most common architectures such as x86
   (patch by Samuel Brederodes).
 * watch: `use_default_colors()', do not force black and white.
+* [NEW] rev: New implementation, not capable of UTF-8 yet.
 * cpio, diff, tabs: Fix duplicated definitions (made/reported by crumbtoo,
   merged by me, Luiz Antônio Rangel). Thanks! --- or better: Merci!
 * rm: Added real support for the POSIX 1003.1(2008) standard, implemented

makefile

@@ -12,7 +12,7 @@ SUBDIRS = build libwchar libcommon libuxre _install \
 	mail man mesg mkdir mkfifo mknod more mvdir \
 	nawk news nice nl nohup oawk od \
 	paste pathchk pg pgrep pr printenv printf priocntl ps psrinfo pwd \
-	random readlink renice rm rmdir \
+	random readlink renice rev rm rmdir \
 	sdiff sed seq setpgrp shl sleep sort spell split stty su sum sync \
 	tabs tail tapecntl tar tcopy tee test time touch tr true tsort tty \
 	ul uname uniq units users watch wc what who whoami whodo xargs yes

rev/Makefile.mk

@@ -0,0 +1,15 @@
+all: rev
+
+rev: rev.o
+	$(LD) $(LDFLAGS) rev.o $(LCOMMON) $(LWCHAR) $(LIBS) -o rev
+
+rev.o: rev.c
+	$(CC) $(CFLAGSU) $(CPPFLAGS) $(ICOMMON) $(IWCHAR) -c rev.c 
+
+install: all
+	$(UCBINST) -c rev $(ROOT)$(DEFBIN)/rev
+	$(STRIP) $(ROOT)$(DEFBIN)/rev
+	$(MANINST) -c -m 644 rev.1 $(ROOT)$(MANDIR)/man1/rev.1
+
+clean:
+	rm -f rev rev.o core log *~

rev/rev.1

@@ -0,0 +1,27 @@
+.\"
+.\" Copyright (c) 2024 Luiz Antônio Rangel
+.\"
+.\" SPDX-Licence-Identifier: Zlib
+.\"
+.TH REV 1 "07/21/24" "Heirloom Toolchest" "User Commands"
+.SH NAME
+rev \- reverse lines of a file 
+.SH SYNOPSIS
+\fBrev\fR [\fIfile\fR]
+.SH DESCRIPTION
+.I Rev
+copies the lines of the specified
+files to the standard output, but
+reversing the order of characters.
+If no file is specified, it reads
+from the standard input.
+.SH NOTES
+This
+.I rev
+supports internationalisation. In
+varietate concordia.
+.SH HISTORY
+A
+.I rev
+command first appeared in UNIX 6th
+Edition.

rev/rev.c

@@ -0,0 +1,121 @@
+/*
+ * rev.c - reverse lines of a file 
+ *
+ * A little bit based on Luiz' implementation
+ */
+/*
+ * Copyright (C) 2024: Luiz Antônio Rangel (takusuman)
+ * Copyright (C) 2024: Samuel Brederodes (callsamu)
+ *
+ * SPDX-Licence-Identifier: Zlib
+ * 
+ * UTF-8 support borrowed from suckless sbase implementation.
+ * Copyright (C) 2016 Mattias Andrée ([email protected])
+ * SPDX-Licence-Identifier: MIT 
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#if defined(__linux__) || defined(__dietlibc__)
+#define _XOPEN_SOURCE 600L
+#endif
+
+#define NULL_BYTE '\0'
+
+static char *progname;
+
+int copy_line(FILE *from, char *to_buffer, size_t to_buffer_size) {
+	for (int i = 0; i < to_buffer_size; i++) {
+		int c = fgetc(from);
+
+		switch (c) {
+			case EOF:
+				to_buffer[i] = NULL_BYTE;
+				return EOF;
+			case '\n':
+				to_buffer[i] = '\n';
+				to_buffer[(i + 1)] = NULL_BYTE;
+				return 0;
+			default:
+				to_buffer[i] = c;
+		}
+	}
+
+	return 0;
+}
+
+bool isutf8chr(char c) {
+	if ((c & 0xC0) == 0x80) {
+		return true;
+	} else {
+		return false;
+	}
+}
+
+void reverse_string(char *string) {
+	int len = strlen(string),
+	    i = 0,
+	    lf = 0;
+
+	lf = len && string[(len - 1)] == '\n';
+	len -= lf;
+	i = len;
+	for (len = 0; i--;) {
+		switch (isutf8chr(string[i])) {
+			case true:
+				len++;
+				break;
+			default: /* "Else", "false", call it what you like. */
+				fwrite((string + i), 1,
+					(len + 1), stdout);
+				len = 0;
+				break;
+		}
+	}
+
+	if (len) fwrite(string, 1, len, stdout);
+	if (lf) fputc('\n', stdout);
+}
+
+int main(int argc, char *argv[]) {
+	progname = argv[0];
+
+	int fdinput = STDIN_FILENO;
+	if (argc > 1) {
+		fdinput = open(argv[1], O_RDONLY);
+
+		if (fdinput < 0) {
+			fprintf(stderr, "%s: %s\n",
+					progname, strerror(errno));
+			return EXIT_FAILURE;
+		}
+	}
+
+	FILE *input = fdopen(fdinput, "r");
+	if (!input) {
+		fprintf(stderr, "%s: cannot open stream at descriptor %d: %s\n",
+				progname, fdinput, strerror(errno));
+		return EXIT_FAILURE;
+	}
+
+	char buffer[BUFSIZ];
+
+	while (true) {
+		int eof = copy_line(input, buffer, BUFSIZ);
+		reverse_string(buffer);
+
+		if (eof == EOF) {
+			if (fdinput) {
+				fclose(input);
+			}
+			return EXIT_SUCCESS;
+		}
+	}
+}